On the subject of cleaning...

[Mamaposaune]

Don't forget to clean the bell section, including the tuning slides!
These before and after pics need no explanation, other than it was from a horn I bought used awhile back, sight unseen. The tuning slide was stuck; when I finally got it free...uggg!

[tbonesullivan]

Did you take it in for cleaning, or did you scrub it and use some vinegar? I'm always amazed at how much mineral stuff builds up in the main tuning slide, which is so far away from any spit contamination.

[JohnL]

I'm always amazed at how much mineral stuff builds up in the main tuning slide, which is so far away from any spit contamination.

You've still got aerosol droplets of spit traveling through the instrument, so some of that's going to be deposited throughout the length of the instrument. There's also a certain amount of moisture that's going to condense on the inside surfaces of the instrument, particularly when you're playing in a cooler environment.

FYI: from what I can tell, the typical dew point of human breath is just under 48°F (9°C). Obviously, there's a lot factors that will influence that, and I would imagine that the air that goes through a brass instrument is significantly moister that normal exhaled air, which would raise the dew point.

(You know, it's weird. I worked with dew point devices for years and never through to check my own dew point)

[Mamaposaune]

I cleaned it myself, including the bell section tubing, (minus the rotor, which was cleaned seperately). Vinegar, cleaning snake, then detergent and water, then a rinse.
Repeated these steps several times over the course of several days.